How Is Top Speed Gained

[Jeff Chambers]

200mph in a street-prepped Fox body? Do you have a deathwish? :^)

Seriously though; the biggest hurdle in your quest is aerodynamics. The Fox Mustang has all the aerodynamics of a wet brick compared to a Ferrari, Vette or other supercar. Though a Mustang's .31 drag coefficient doesn't look that bad compared to a Ferrari's .23 drag coefficient (I'm not sure of the actual numbers here, just making them up to demonstrate the point), frictional drag is a function of the velocity SQUARED and frontal (projected) area. Any of the supercars (for lack of a better term) have a much smaller projected area than the Mustang. If I recall, the Fox has an area of something like 34 ft^2. I'd imagine that the Vette has something on the order of 24 ft^ max; very low slung profile. That's a factor of 1.42. Now since drag is a function of velocity squared, the amount of horsepower required to go from 120mph top speed to 200mph is about 2.78. Comparing that Vette's factory 350hp to a Mustang's stock 205hp, there a factor of 1.70. Multiply that 1.70 by the area advantage of 1.42 and the drag coefficient advantage of 1.34 and you've got a combined factor of 3.26 which pretty much says that the Vette can get upwards of that 200mph goal; and I haven't even figured in the differences in weight. Now if you go using a 60's platform Mustang, expect to need even more HP to reach that goal since they have an even worse drag coefficient and even more frontal area. There are many, many more factors such as parasitic drag (different than the primary frictional drag), ground effects, rotational inertia, on and on and on. If it were easy to build a 200mph street car, you'd see the pits at Indy and Daytona filled with Mustangs.